The Dow Jones Industrial Average plunged about 400 points in early trade Monday as a 7% drop in Chinese stocks stoked a global selloff in stocks.The Dow DJIA, -2.09% plunged nearly 411 points to 17,015, led by a drop in DuPont Inc. DD, -3.64% and American Express Co. AXP, -2.67%The S&P 500 SPX, -2.00% fell about 45 points to 1,998, led by a decline in technology stocks, financials and industrials. Only the S&P 500’s energy sector showed a modest gain as Middle Eastern tensions helped lift crude-oil prices.The S&P 500-tracking “SPY” ETF opened down nearly 2%. According to Bespoke Investment Group analysts, since the SPY SPY, -1.91% began trading in 1994, the ETF has only opened lower on the first trading day of the year twice in 22 years, and it has never opened lower by more than 1%.Meanwhile, the Nasdaq Composite COMP, -2.68% cratered by 138 points at 4,869 as tech stocks took the brunt of Monday’s tumble.